JPS59205490A - Manufacture of anode and method of lowering hydrogen overvoltage in chloroalkali electrolytic cell - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an improved method for producing a cathode for a chloroalkalkali aggregation tank, and a method for preparing a cathode for a chloroalkalkali distillation tank.
h. Concerning a method for increasing the pressure to lLV.

The production of caustic and hydroxide by brine production is well known in the art. The solution is generally carried out in a positive chamber, consisting of a coffin, a cathode, an anode chamber and a negative chamber. In one of the more modern types of such electrolyzers, these two chambers contain fluorine- They are separated from each other by a containing cation exchange membrane.

Such electrolyzers can be operated more efficiently and at +14 Vr because the redundancy is increased and the operating voltage is lowered. Very large daily due to brine electrolysis, it
F
Even very small improvements in lt flow efficiency and operating voltage will result in x amount of money saved and a large amount of energy saved.

The electrolyzer operating voltage consists of a number of component parts, one of which is the electrolytic drop at 1 mNO, known as the hydrogen overpotential.

Reducing the hydrogen overvoltage results in lowering the total pressure of the electrolyzer, thus making the C process even more economical.
Ru.

U.S. Pat. -L, J transition metals are added to catalyze the generation of hydrogen % scraps. In one example, a solution of fdt-iron is added to the catholyte chamber. However, the effect is short-lived and to maintain the effect the transition metal sound is added at intervals of 7 days and 10 days.
Sometimes it has to be added repeatedly every 6:1. Therefore, equipment is required to separate the transitional metals that contaminate caustic products.

U.S. Pat. No. 4,160,704 discloses a method for reducing the cathode hydrogen overpotential in an alkaline electrolyzer, in which gold in the form of a cation selected from a group including iron, cobalt, and others is disclosed. A solution of 1f4 ions is introduced into the chanting solution. This method smells
The C1 combined metal cation solution was fed into the cathode chamber (often at 11 + 20 hours) and circulated back through the cathode chamber for 1 hour; however, during these operations In the presence of caustic alkali in the cathode chamber, the introduced ferrous cations precipitate as insoluble ferrous hydroxide in the absence of a complexing agent such as tartaric acid monosalt. Alternatively, the iron element could be added to the test chamber, or a stainless steel cathode chamber could be used; in the latter case, the operation was 27
After several days the cathode overvoltage was reduced, but the cathode chamber itself was corroded.

US 13i1% Permit No. 4.29 A447 VC, RIA
A cathode for reducing the hydrogen overpotential in a7A/potassium is disclosed, which has particles consisting essentially of α-iron crystals adhered to the surface of a butyrode substrate: The current method is to deposit particles consisting of a specific electrolyte and α-iron particles into the air device, and then apply an electric current to the electrical equipment Wi? -n
It can be a th membrane type aa alkaline peeping tank. However, this method now suffers from the following drawbacks: (2) some of the iron particles deposited in the fl+ cathode chamber are discharged from the tank along with the caustic product; Sludge completely forms at the bottom of the chamber. (3) Some of the iron particles sometimes adhere to the ion exchange layer, causing iron precipitates in the membrane, and when this becomes quite large, it causes peeling and direct pressure. It has been found that this method has the disadvantage that it results in an M size of .

It is therefore an object of the present invention to provide an improved method for making iron-activated cathodes for chloralkali municipal decomposition.

Another objective of the present invention is to provide a method for reducing the culvert voltage of an AA alkaline tank.

The above object has been achieved by the present invention, which briefly describes - in the aspect - consisting of an Fe"ste element and optionally hydrogen, characterized by a green color,
11. The process consists of creating an iron-activated cathode by adding an iron-containing anion (usually referred to as a ferrite ion) to a chloralkali nitrogen bath.

and a necessary cation exchange between the anode chamber and the cathode chamber, the anode chamber containing a brine aqueous solution,
The cathode chamber contains an aqueous caustic solution, and the method includes the steps of: (α) completely introducing an aqueous solution containing ferrite ions into the cathode chamber; (b) No current is passed between the anode and the cathode until a precipitate of iron has formed on the surface of the cathode.

According to the present invention, the anode, cathode, anode chamber,
, and V) a method for lowering the pressure and pressure of a tal-alkali wakaji 4' shield consisting of a fluorine-containing cation separating the two chambers, and V) A method is provided which consists of placing 1 g of ferrite ion-containing water in the negative chamber.

In addition, according to the present invention, a chloralkali surface dissolving tank consisting of a fluorine-containing cation exchanger; An improved method is provided in the electrolytic method for frying, which consists of adding aqueous solution containing ferrite ions into the cathode chamber. A solution containing Fe" bound to 1+;':0 is added to the cathode in chloralkali% I'4I4 soda.

As is well known in the art, the main and essential components of a diaphragm alkaline electrolyzer are an anode chamber, an anode chamber, and an anode chamber. It consists of a cationic cathode, and a cationic membrane located between and separating these two chambers. an aqueous brine, such as a saturated sodium chloride solution, is supplied to the anode chamber;
Water or dilute caustic solution is then supplied to the cathode chamber. Caustic and hydrogen are formed in the anode chamber and chlorine is obtained from the anode chamber along with depleted brine.

The present invention is applicable to shades having various shapes and shapes.

Examples include those made of nickel, stainless steel, mild steel and mild steel with a nickel surface such as nickel plated or Raney nickel, in the form of sheet, a-rad or exnoded metal. Poling with a Raney nickel surface is described, for example, in U.S. Pat.
No. 16,804, No. 4.169.025 and No. 3.6
37.437.

In the present invention, a chloralkali 'PWn P,1 (i) containing a cation V exchange membrane of known 1-r::# seeds suitable for use in a suspended type III electrolytic layer is used. be.

One such fluorine-containing polymer is disclosed in U.S. Pat.
, No. 282.875, No. 4.085.071, No. 4.
176.215 and 4.267.364k; and South African Patent Publication No. 7810022'25; 4 listed in
Including, but not limited to, those made from 1J-mers.

Akira Motoyaku is applicable to a wide range of operating conditions of Yamaf) Tl, 4+717, but the usual type of fluidity 7.
5 to 50 amperes/dm, i.e. 0.5'7” or less to 3 amperes or more/Ln2), temperature 75 to
90℃, caustic alkali formation A degree lO~40 city...-%,
A9 size finds utility in electrolyzers operated at discharge brine concentrations of 15-25%.

In most typical industrial-sized diaphragm lyco-alkali reactors, a 1dj separation between the anode and the cathode is used.
That is, about 2 to 8 dishes. ``When assembling the 1st column for M use, the cylindrical column can be attached at a distance from the two tubes 4j and also at the anode or closer to the 1j pole, preferably closer to the anode.

Because of the possibility of deformation (based on expansion of the membrane in the aqueous solution and/or pressure fluctuations in either the catholyte or the anolyte), the membrane is not actually connected to either the anode or the cathode. will come into contact with. One preferred method of operation is to space the cathode a nominal distance from the membrane, generally about 1 to 61 mX, and maintain the catholyte pressure at a suitably higher pressure than the anolyte pressure that forces the membrane against the anode. The objective is to maintain the stability during this period. In another suitable arrangement, the cathode used is a mesh of exogunned metal with a spacer bar about three curtains thick attached to one vaguely facing surface; Then, the electrolytic cell is assembled with a distance of about 3 mJ# from the surface of the anode and 11σ close to the surface of the cathode. .

In this arrangement, the cell is operated with the anolyte head higher, holding it opposite the 11...k spacers, thus providing a liquid 11 gap for the iTh(lit). The electrolyzer may also be of the type referred to as a zero-to-one gap; in such an electrolyzer both the anode and the cathode are placed in contact with the cation exchanger, and one is the aperture tla * % e.g.
An electrolytic cell which is perforated or microporous and allows the passage of gases and gases. The pattern can be carried out with an electrocatalyst on at least one surface thereof to form a membrane/box-bar complex (e.g. as described in British Patent No. 2.009.788 A). ); the membrane has a gas- and adult-permeable porous non-porous, polar layer thereon (e.g. British Patent No. 2,064);
, 586A); and also membranes with roughened surfaces (e.g., described in British Patent No. 2,043,108A).Arrangements particularly suitable for the practice of the invention include such non-electrode layers. A membrane with a narrow gap was used for one time in a narrow gap configuration.

In the present invention, it is a solution of ferrite MaW, u sodium or potassium ferrite in a concentrated alkaline solution suitable for one-time use, and the caustic alkali concentration is, for example, 40 to 50% by weight of sodium hydroxide or 40% of potassium water RNide.
~S2-@arm%. Most suitably, the synergic solution is an aqueous solution. Such a solution is treated with tl and LILI by a known method.
It can be made by heating caustic alkali metal with iron particles.

Unreacted particles are easily removed by filtration or centrifugation. The obtained ferrite solution can best be stored by avoiding contact with air to prevent destruction of ferrite ions due to V oxidation. The chemical formula for sodium ferrite is expressed as Nα FeO, and when it consists of Na4CFe (01,/J's 1), the ferrite ion is further expressed as Fed2'' or 1fFeo, -. It should be noted that there is sometimes disagreement in the chemical literature regarding the use of the term ferrite; In this specification, Co
The heavy usage of the term "ferrite", as used by T.L. and Ill'1lkinson (see below), has been adopted and refers to fiFttf-containing anions.

The amount of ferrite to be added to the catholyte does not appear to be critical. When the solution is added to the catholyte, the covered area (1 nclrbded area) is 1 m”
The hydrogen overvoltage can be increased from a small amount such as Fe2fl per 1 d of sodium ferrite (LOg of sodium ferrite/inclusive area of the cathode) to as large as FgTδg per 1 d of inclusive area of the cathode (350 g of sodium ferrite/inclusive area of the cathode). It was confirmed that M is effective in reducing 1 encompassing area of the cathode is the shade wfL + generally flat shape or fc
is generally the outer contour i! J!
means the total area encompassed by. The effect of reducing the voltage is 0.1-0.4 yj? compared to the voltage of an equivalent electrolytic cell with a non-handed cathode or the pressure of Qil where the addition of 7-elite is carried out. ) The low range was over K.

1) The operation of the poles at lower voltages has little or no deterioration in operability during the operation period. In order to maintain l and ψ productivity, there was no need to add ferrite to YG4, and it was confirmed that 80 days were required.

To thoroughly add the ferrite solution, (f+'; t, avoid contact with air to avoid 1'''R conversion of I+ ferrite ions, and (2) 8' current of caustic alkali is approximately 32%. At 11C, iron hydroxide will precipitate, so avoid diluting it with water. It is best to install it at a location far from the exit.

When a concentrated caustic solution of ferrite is added to the catholyte of the chloralkali Itr + M in the operation room 5, the sliding voltage may temporarily increase in a short period of time, but this is due to the concentration of the concentrated caustic alkali IJ &r. It is believed that this is due to the increase in foaming in the shade chamber. It is approximately 1 to 16 minutes after ferrite is added that the tank quasi-pressure decreases compared to before ferrite is added.
It will be recognized after 1 hour.

The activated cathode thus produced carries a black precipitate (2) which can be easily scraped from its raw substrate; It is sufficiently attached that it can be transferred and removed without disturbing the precipitate.

The advantages of the present invention over conventional methods are that it is quick, convenient, reproducible and inexpensive; only one addition is required to obtain a lasting effect; continuous or repeated additions are not cheap; Auxiliary device I for conditioning the denaturant solution! In combination with iron, complexing agents such as tartrates and auxiliary low overvoltage metals such as nickel, chromium or molybdenum are not necessary at all.
%N4', alkali +='1 product is hardly contaminated.

Considering that the polarization of the alkaline I't fl bath is negatively charged, it is surprising that negatively charged ferrite ions are highly effective in bringing about the activation of the cathode. be. Ferrite ion is applied'r11
It might be expected that the pressure shadow 1.1" would move towards 11" and smudge it by 1.1", but the smear 4i4 did not occur at 1lil.

Examples Sodium Ferrite I! Preparation of solution 50% water 1τψ
Add 1% iron fine powder 8y to sodium chloride water #Kin400me
+i and heated this mixture at about 142°C for 16 hours, 1j
It was refluxed for 14 hours. The mixture was filtered to remove undissolved iron 6y; thus the iron 2I reacted. A transparent p-liquid with a dark blue-green color characteristic of ferrite ions was diluted with deionized water to about 40% sodium hydroxide, strength 1, and stored under a nitrogen atmosphere. Although it is unclear, this procedure did not produce a monochrome ferrite solution, but rather a yellow-green solution, which is not effective in making iron-activated cathodes. The method is essentially
n and M.Filkinson, Advαnced I
norga-nic Chemistry, Inter
science.

1972, p. 860 - Green N
This is a method for producing crystals of a4(Fe (011) l).

Examples 1-4 These examples consist of a glass anode chamber and an acrylic resin cathode chamber, and one anode and one cathode separated by about 2 to 3 mm and separated by an ion exchanger. A small chloroalka 'J electrolysis' (Qa) was used.

The anode was a dimensionally stable anode wave-glazed with ruthenium dioxide and titanium dioxide. The membrane is methylnocufluoro
(4,?-Dioxer-5-methyl-8-)nonoate)
and tetranororoethylene 10 ” 0 'j
c) A 51 micron (2 mil) layer of the copolymer and HinoR-7 (3,6-thioxer 4)
-Methyl-7-ocranesulfonyl fluorite) and tetrafluoroethylene, consisting of a 152 micron (6 mil) thick layer of a copolymer having an equal part of -1100'5c, with a layer of predominantly 10-sulfonyl polymer in it. has a woven fabric of fluorocarbon monofilaments, and the carboxylic acid and sulfonic acid groups are hydrolyzed to form their sodium salts, and during the carvone pass layer all B5 poles are formed. It was placed facing the direction '1. To the positive + @Hayabusa, IJumu-naiwa-m solution (chloride purified by ion exchange to reduce the calcium ion production to 5077, p, b, or less) is supplied, and 1ON caustic alkali 17 is supplied to the cathode chamber. Water (diluted caustic in the cypress initiation process) was supplied at a rate such that f.
Electrolysis was carried out at 90° C. and 3 kA/rrt (2Δsil), with 2001//l in the discharge brine.

OperationUsing this electrolytic cell which produces caustic alkali and hydrogen in the cathode chamber and chlorine in the anode chamber under steady state conditions, the above ferrite solution is pumped into the chamber at +'3% of the catholyte solution. It was fed through a tube leading to a point near the center of the cathode on the surface. Typically, the sliding voltage increases by about 0.1 to 0.3 volts during this ferrite addition process, due to increased bubbling in the cathode chamber caused by the addition of concentrated caustic solution. It is biased towards what should be attributed. However, this increase in tK quickly disappears when the supply is stopped, and the voltage continues to decrease to a value of F after the initial steady-state deafness for 1 to 16 hours. Data of Examples 1 to 4 Examples 1 to 4
In No. 3, the ferrite solution was introduced over several hours. The weight of the ferrite solution was 0.4 g of ferrite per 100 kg, or 85 g of iron. In Example 4, the ferrite solution was added over a period of 10 minutes.

In Example 1, four soft @-3 resistors were welded to a mild steel cathode substrate on the side facing the membrane,
This shade 4/spacer silk proboscis was plated with nila gel. No spacer was used in Gun Examples 2-4. .

When the tank was dismantled at the end of each experiment, a black precipitate was found on the surface of the cathode; the precipitate was easily removed by rubbing, and in order to prevent damage to the precipitate, it was necessary to remove the precipitate. The cathode must be handled with care.

In Example 3, after 6 days the electrolyzer was shut down for 6 hours and allowed to run for 3.63 yK silt for 3 days before shutting down again.

At the end of the 25th day, a leaking gasket required the tank to be shut down and dismantled;
It is believed that some of the finest iron deposits were lost.
-Therefore, the deposited iron on the l'is i' cathedral was removed using an old method. When the cleaned 1-piece was reassembled, the IR pressure was close to the value before the addition of ferrite.
But ferrite melt! 'The voltage is 3 again in the old J1
．． Mr. Lee dropped to 60 delts, and 53 days after singing 1i4]t
Hikari was turned over without any decrease in his ability to manipulate, and was subsequently suspended.

In none of the above examples, the cypress was never shut down due to deterioration in the operability of the activated I-kai I-Ei. All stoppages were made to prepare the vessel for the next experiment and to analyze the IY 11iS superprecipitate.

In Example 1, after the experiment was completed, the cathode was removed from the bath and gently rinsed with water. The X-ray powder pattern of the coating on the cathode was detected, and the coating was found to be a combination of α-Fe0, E, and V.
It was shown to be a 0:50 (shelf, omitted) mixture.

Industrial Applicability The present invention is widely useful in the chloralkalinity industry as it provides more efficient and economical operation of OA alkaline electrolysers. For example, in a plant that prepares 1000 metric tons of caustic alkali per day, the current efficiency is 95%.
, operating at a power cost of $0.05/kilowatt hour,
Operating voltage drop 0.1 volt per two years $1.280.
Savings exceeding OQ O can be obtained. In addition to the actual monetary savings, you will also save on world-class energy reserves.

Both the method of manufacturing an iron-activated cathode and the method of reducing hydrogen overvoltage in an aro-alkaline electrolyzer are features of the present invention and are reliable and effective. These methods are i generation M,
This can be easily done at any point during the tank operation process. During the cathodic activation, no delay in the delay or initiation of γf'N is required, and no circulation of the denatured molten acid is required. Kai@
Achieved by using only ILi ferrite; the pond's low overpressure metal ions with ferrite! 1” total 2
,9. I don't feel safe going in at all.

Special ex-Russian: 1 person outside of E.I. DuPont de Nemois Rand Company

Claims (1)

[Scope of Claims] l, an anode chamber, an anode located in the anode chamber, a cathode chamber, a cathode located in the chamber to the anode chamber, and a cation between the anode chamber and the cathode chamber. A method for making an iron-7 aged cathode from the cathode of a chloroalkaline IJ electrolytic cell consisting of an exchange membrane, the anode chamber containing a brine aqueous bath solution, and the cathode chamber containing a caustic aqueous solution, the method comprising: α) An aqueous solution containing ferrite ions is placed in the cathode chamber, and (6) a precipitate consisting of iron is formed on the surface of the cathode. A method for making an iron-activated cathode characterized by passing a full current through the t-river. λ The superpole is made of nickel, stainless steel, mild steel or mild steel with a fl nickel surface. Claim 1 4. The method according to claim 2, wherein the cathode is nickel. 4. The ferrite ion-containing aqueous bath is a solution of sodium or potassium ferrite acid in an aqueous caustic solution, The caustic alkali aqueous solution is caustic alkali 40~
2. The method of claim 1, wherein the method is a 50% by weight solution. 5. Patent W in which the sodium or potassium ferrite solution contains 0.1 to 5 I of iron per liter of solution
+'A range of search method according to item 4. 6. The method according to claim J5, wherein the solution of sodium or potassium ferrite is added to the cathode chamber in an amount containing from 1 to 5 Ii of iron per li of area covered by the cathode. 7. The anode, the anode, the cathode chamber, and a fluorine-containing cation exchange membrane that fills these chambers.
A method for lowering the operating voltage of an alkali decomposition tank, the method comprising introducing a Vt ferrite ion-containing water bath m-2 into the false chamber. How to lower. 8. The method according to claim 7, wherein the cathode is made of nickel, stainless steel, steel or mild steel with a nickel surface. 9. The method according to claim 8, wherein the cathode is nickel. 10. Claim 7, wherein the ferrite ion-containing aqueous solution is W4 of sodium and potassium ferrite in a caustic alkali aqueous solution, and the caustic alkali aqueous solution is a caustic alkali 4() to 50I% solution.
Method of describing burial mounds. 11. The method of claim io, wherein the solution of sodium and potassium ferrite contains 0.1 to 5 g of iron per liter of bath liquid. 12. The solution of sodium or potassium ferrite is added to the hypnosis chamber in an amount of 1 to 5 per 1 m' of area covered by the 1 m
Claim 11: g of iron is added with a ringer.
The method described in section. 13. In a method for electrolyzing brine in an alkaline electrode WlWi consisting of an electrode, a cathode, an anode chamber, a cathode chamber, and a fluorine-containing cation exchange membrane separating these chambers, an aqueous solution containing ferrite ions is provided in the cathode chamber. Improved brine electrolysis method with addition of solution. 14. Claim 13 in which the shade is nickel, stainless steel, mild steel, or mild steel containing nickel on the surface
The method described in section. 15. The cathode is made of nickel. Claim 111 No. 1
The method described in Section 4. 16. The ferrite ion-containing aqueous solution is mixed with a bath solution of sodium or potassium ferrite in a caustic alkali aqueous solution, and the caustic alkali IJzic% solution is mixed with a caustic alkali 4
0 to 50 rliiii filling fluid of cow FW
The method described in Section 13 of Hekokufuji. 17. The nato IJ + 1 valley tW of cum or potash cumferrite contains 0.1 to 5 g of iron per liter of bath liquid + '4? The method of requesting permission - Chapter 16, Chapter 61. 18. The sodium is also [2〈7d liquid of potassium ferrite is 1) the inclusion surface of the B pole to the back 4Jf1 rr
? 1~SF per hit! [t11] The method according to claim 17, in which the iron-containing agent is added.